Undoubtedly the most underrated attraction of San ...

Undoubtedly the most underrated attraction of San Francisco - not that it was empty, very far from it, but from how incredibly interesting their exhibitions and experiments are inside the exploratorium, I would've expected it to be boiling over with people. Only makes it more enjoyable - and an even better reason to go - that it's only moderately full. Full of fun and interesting exhibitions - for adults, too.